#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=2e3+1000;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
char str[maxn];
LL cnt[30];
int main(void){
   cin.tie(0);std::ios::sync_with_stdio(false);
   LL t;cin>>t;
   while(t--){
      LL n,k;cin>>n>>k;
      for(LL i=1;i<=n;i++) cin>>str[i];
      memset(cnt,0,sizeof(cnt));
      for(LL i=1;i<=n;i++){
        cnt[str[i]-'a'+1]++;
      }
      LL ans=0;
      for(LL i=1;i<=n;i++){
          LL len=__gcd(i,k);
          LL block=i/len;
          LL sum=0;
          for(LL j=1;j<=26;j++){
             sum+=cnt[j]/block;
          }
          if(sum>=len) ans=max(ans,i);
      }
      cout<<ans<<"\n";
   }
   return 0;
}
